An understanding of apertures is important to appreciate the advantages of one lens over another.
The wider the aperture, the greater the amount of light that can pass through the lens. This means the shutter needs less time to expose the image. Wider is often spoken of as ‘faster’.
A common application of wider apertures is photographing portraits. Areas will appear blurred in front of and behind the plane of focus, while your model can still be sharply focused and exposed correctly through the wide aperture.
This is a desirable result because the viewer’s eye immediately acknowledges the point of the photo – the model’s image is not in conflct with sharply captured elements in the scene. Instead, the only crisply focused element is the model.
Smaller apertures allow less light through, which means the shutter will open longer to expose the image. These lenses are often referred to as ‘slower’ lenses.
Wider aperture lenses are generally more expensive. Their glass elements usually require a more serious manufacturing effort. The wider aperture Canon L lenses are a good deal more expensive than slower non-L lenses.
However, there are fast – or wide aperture – lenses that are not L lenses. The L lenses have a better build quality but Canon buyers need to weigh up whether to spend the premium for the L versions of a 50mm, an 85mm or a 135mm lens.
A 50mm f/1.2 L lens costs around 14 times the price of a 50mm f/1.8 standard lens. And you can get yourself an 85 f/1.8 for better than a fifth the cost of an 85mm f/1.2. The 135mm f/2 L is twice the cost of a non-L 135mm f/2.8.
Thanks to their fast apertures, the cheaper lenses mentioned above can still produce great images. And, in the minds of some photographers, the difference that f/1.2 provides over f/1.8 is not enough to justify the added expense.
The good thing about investing in L quality lenses (Nikon has its own pro quality lenses too), however, is that they are built to last. It’s not unusual for pro shooters to get three decades or more out of their pro quality lenses. And, despite the already exhilarating shallow depth of field offered by an f/1.8 aperture, the razor thin focal plane at f/1.2 is a seductive and unique proposition for all who are involved in the pursuit of excellence.
Lenses are purpose-built for specific types of photography. From 50mm to 135mm is the range that serves portrait photographers. Consensus is that 85mm is the optimum focal length for portrait shooters.
From 135mm to 300mm is good forindoor sport, upwards of 300mm for outdoor sport.
Photographing surfers in action requires at least a good 300mm lens with longer lenses being preferred to bring the action closer to view. This is also the sentiment of many bird photographers, who find that anything shorter than 400mm is too short.
Landscape photographers are happiest with wide angle lenses between 14mm and 24mm.
Macro photography offers few options. The most popular macro lenses are around 100mm because it gives enough working distance to allow you to photograph an insect without scaring it away. Some photographers prefer the extra working distance of a 150mm macro lens.
The shorter focal length macro lenses are more dedicated to inanimate subjects, such as jewels and coins etc.
Zoom lenses are a relatively recent innovation and the best of them achieve image quality to rival prime (or fixed focal length) lenses. There is a tendency, when using zooms, to forget that using your feet can often provide you with a superior vantage point.
Finally, be cautious when buying a third-party lens. Performance quality varies significantly where the lens is built by a different manufacturerof the camera.